Verizon's historical share of iPhone shipments suggest that Apple is on pace to have moved at least 32 million handsets last quarter.

Analyst Maynard Um of Wells Fargo Securities provided a breakdown of Verizon's importance to overall iPhone sales on Thursday. He noted that over the last six quarters, Verizon has accounted for an average of 11.6 percent of Apple's total iPhone shipments.

Verizon officially announced earlier Thursday that it activated about 3.9 million iPhones in the just-concluded September quarter. That accounted for 51 percent of all smartphone activations at America's largest wireless provider during the three-month period.

Verizon's 3.9 million iPhone activations would imply total shipments of 33.5 million iPhone units for the September quarter, if the carrier's historical 11.6 percent share were to hit the mark.

However, in the preceding quarter, Verizon took a slightly larger 12.2 percent share of total iPhone units. If that were to happen once again, it would imply total units of 31.7 million for the period.

Both of those numbers are higher than Um's forecast of 31 million iPhone units for the September quarter. The calculations are also higher than the 26 million iPhones Apple sold in the September 2012 quarter.

Apple's fourth quarter of fiscal 2013 includes over a week of sales of both the iPhone 5s and iPhone 5c, both of which went on sale in late September. Sales of those devices reached 9 million in the first three days alone.

Apple will reveal exactly how many iPhones it shipped in the September quarter in its own quarterly earnings report, scheduled to be release after markets close on Monday, Oct. 28.